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Harold K. "Hal" Lipset, a San Francisco private investigator who died Monday at age 78, will be remembered not only for cracking some of the nation's most famous cases, but for lending his behind-the-scenes know-how to the Jewish world.

As a two-term president of the regional American Jewish Congress in the mid-1970s, the internationally renowned gumshoe "would open up doors for us that we couldn't open ourselves," said Joel Brooks, a former executive director of the AJCongress who worked alongside Lipset. "He had incredible connections."

A private eye for nearly half a century, Lipset died of heart failure at San Francisco's Mount Zion Hospital, following surgery for an abdominal aneurysm.

Credited with helping turn the detective business into a respectable venture, he had a list of clients that included law enforcement agencies, government entities, attorneys, businesses, and private citizens.

His work landed him everywhere from the U.S. Senate, where he served as chief investigator for the Watergate committee, to seamy hotels, where he burst into dark rooms to photograph philandering spouses locked in clandestine embraces.

In the Jewish world, where he also served as AJCongress national vice president, "his skills as a private investigator were often called upon to aid his people," Brooks said.

Under Lipset's leadership, the AJCongress tackled the cause of Soviet Jews with particular fervency.

"He had very good personal contacts in the Soviet Consulate locally," Brooks said. "They were put to good use in the case of Soviet Jewry." Later, he got involved in attempts to rescue Ethiopian Jews from their war-torn nation.

Whether Lipset ever brought to the Jewish world such pioneering surveillance tactics as bugging roses or martini olives, Brooks would not say. Once, the crafty detective hid a microphone in a bar of soap, which he took with him into a Turkish bath.

For moves such as these, Lipset is believed to be the inspiration for the private investigator played by Gene Hackman in the 1974 movie "The Conversation." Lipset served as a technical adviser on the Francis Ford Coppola film.

Born in Newark, N.J., in 1919, Lipset attended the University of Pennsylvania before transferring to U.C. Berkeley. He enlisted in the Army in 1941, serving as both lieutenant and captain in the military police and winning a Bronze Star in combat. The military sent him to an investigators' school in Georgia.

After the war, he and wife Evelyn moved to San Francisco. He opened his own business, Lipset Service, in 1947.

In his decades of work as a detective, he tackled thousands of cases. "He felt that an investigator was not worth his salt unless he took every case," said Patricia Holt, San Francisco Chronicle book editor and Lipset's biographer.

"He didn't discriminate or judge. It didn't matter to him if you were asking him to investigate a murder or break down a hotel door to photograph an illicit couple in bed for a divorce case. He did all of it."

Widely considered the Bay Area's premier investigator, Lipset served as president of the World Association of Detectives and president of the Professional Investigators Association of California. He directed the Hastings School of Law Trial and Appellate Board of Advocacy, and taught the fundamentals of investigation at the University of San Francisco Law School.

Holt credits the detective with raising the standard of investigation in the post-war era.

"Before Lipset's service, PIs were operating under the stigma, largely true, of being pretty sleazy operators who had been kicked off the police force for alcoholism or things like that," she said.

"He was able to bring discipline and professionalism to the private sector. He and his wife built their office around a system they could trust and that their clients could trust. Trust is everything in that business."

He built trust, she said, by fiercely guarding the confidentiality of clients while at the same time being open enough to reveal some of his own secrets and methods.

As a case in point, she cites the 1965 robbery of a million dollars worth of jewelry from San Francisco's Shreve and Co. Lipset tracked the thieves through Europe and finally nabbed them in the Canary Islands.

Throughout that adventure, Lipset kept eager San Franciscans up to date on the chase by sending dispatches back to the late Chronicle columnist Herb Caen. "Everyone was privy to how he was doing," Holt said.

In between his globetrotting, Lipset found time for community service. He served as chair of the Bayview Hunters Point Foundation and president of the board of the Museum of the City of San Francisco.

At AJCongress, he helped start a program, Legal Services for the Elderly, offering free legal services to seniors who could not afford an attorney. The program, which originally met in the Jewish Community Center of San Francisco and served mostly Jews, expanded rapidly in both size and scope.

Eventually, the program got federal funding. At one point, it became one of the largest legal service programs for elderly in the state.

Lipset "had an abiding passion for social justice and human rights," Brooks said. "He was really a mensch."

A funeral service for Lipset was held yesterday at Congregation Sherith Israel in San Francisco.

Lipset is survived by two sons, Louis Lipset of San Francisco and Lawrence Lipset of Mendocino. He has one grandchild. Lipset's wife, Evelyn, died in 1964.